Allowance for loan losses and credit quality Narrative Data (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) loans	Dec. 31, 2018 loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Resturctured Loans, Number to Subsequently Default		0
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Resturctured Loans, Number to Subsequently Default	1
Troubled Debt Restructured Loans to Subsequently Default, Principal Balance | $	$ 79